4 J. Barrell — Relations of Subjacent Igneous 



province of the soutliern Appalachians no post-Cambrian 

 intrusives were mapped by the geologists who worked in 

 that field, whereas much of the metamorphism was of 

 post-Cambrian date, led the writer to hold the matter in 

 considerable reserve, and refrain from publication. But 

 in 1907 Keith in the Pisgah, North Carolina, f olio^ noted 

 the undetermined age of the Whiteside granite which 

 occupies large areas in North Carolina and Georgia, and 

 stated that it might be as late as Carboniferous. In the 

 geological map of North America issued in 1911, large 

 granite areas in the southern Appalachians are mapped 

 as post-Cambrian; and in the Ellija}^, Georgia, folio.^ 

 1913, La Forge and Phalen state, in regard to the small 

 patches of younger granite on the east and the gabbro 

 dikes cutting the Lower Cambrian on the west, that from 

 their structural relations both are believed to be of late 

 Paleozoic age. This increase of knowledge brings the 

 late Paleozoic orogenic history of the southern Appala- 

 chians into closer kinship with the late Paleozoic history 

 of New England. It was the study of the latter field, in 

 addition to some years of experience in the Cordilleran 

 province, which led to the development of the ideas 

 expressed in this article. They apparently may be 

 extended to cover the southern Appalachians, and seem 

 to imply enough generality of application to warrant 

 publication. Various additions have been made to utilize 

 the contributions bearing on this subject made by others 

 in later years. 



Subjacent Igneous Invasion in Mountain Provinces. 



Suess and Daly have in separate volumes broadly dis- 

 cussed in recent years the phenomena of batholithic 

 invasion. Adams and Barlow, Sederholm, and others 

 have made clear many detailed illustrations. The cumu- 

 lative effect of all this work is to show the widespread 

 occurrence of those bodies named batholiths by Suess, 

 which he, in common with the French geologists, held to 

 broaden downward ^'bis in die ewige Teufe", and which 

 Daly classifies as subjacent igneous bodies in order to 

 distingTiish them from those clearly injected into the 

 crust. In broad regions, these are now known to be of 

 Paleozoic, Mesozoic, and even of Cenozoic age, extending 



^ A. Keith, U. S. Geol. Survey, Geol. Folio 147. 



^ L. LaForge and W. C. Plialen, U. S. Geol. Survey, Geol. Folio 187. 



